共查询到20条相似文献，搜索用时 31 毫秒
1.
Timber floors are by far the most common structural systems used in wood-framed residential buildings,and are the only systems with which human occupants are in constant physical contact.In dwellings,the floor vibration due to walking often brings discomfort to the occupants.Designing a house that controls the agonizing vibration of floors is a difficult problem.The vibration performance of five solid wood lumber joist floors was studied as were subjective opinions of evaluators.The 1KN static deflection and fundamental natural frequency were selected as two evaluation indexes of the vibration performance.The results show that when the ratio of the fundamental natural frequency to 1KN static deflection's 0.44 power is larger than 20,the solid wood lumber joist floor can be classiified as acceptable. 相似文献
2.
Steel concrete composite slim floors with the steel beam encased in concrete floor slabs have many advantages, including low structural height, high fire resistance and rapid construction times. These features make such floors a promising for use in multi storey steel buildings. We established a 3D finite element model of a monolithic composite slim floor using the ANSYS software package. We analyzed the loading capacity, deformation behavior, natural vibration frequency, the influence of reinforcement, and the concrete in the floor rib under a uniformly distributed vertical load. We calculated the effective width of mid girder and secondary beams. The following conclusions can be drawn from the analysis results: First, monolithic composite slim floors possess high loading capacity for common buildings. Second, the concrete rib and reinforcement ratio in the rib have significant effects on floor loading capacity. Third, calculation of effective primary beam width should be based on analysis of monolithic floors rather than single beams. 相似文献
3.
To explore the vibrating frequencies and rational impact factors of multi-span skew bridge, the recursive algorithm of vibrating frequency and finite element formulations of static and dynamic analysis are established for uniform section multi-span continuous skew bridge. The first five order frequency changes of equal-span multi-span continuous skew bridge and unequal-span multi-span skew bridge are compared. The interaction of vehicle-bridge system for two-span skew bridge is analyzed. The history curves for deflection and moment of middle-span are presented. The influence of obliquity on dynamic deflection and dynamic moment as well as the influence of vehicle velocity and obliquity on impact factors of deflection and moment are investigated. Results show that the fundamental frequency of multi-span skew bridge is identical to that of single span skew bridge. The higher order frequencies of single span skew bridge are distributed in frequencies of multi-span skew bridge, which mix other vibrating frequencies. The more the span number is, the more the other vibrating frequencies mingle. Obliquity has an important influence on dynamical characteristics of skew bridge. Impact effects of vehicle have no harmonious changing rule with vehicle velocity and obliquity. The impact factors of deflection and moment are different for skew bridge. 相似文献
4.
Dynamic analysis of a new Nano-CMM(Coordinate Measuring Machine with nanometer resolution) structure is introduced,including vibration characteristic analysis and vibration response analysis.The aim is to assess and analyze dynamic accuracy of structure.Modal and harmonic analysis were made by ANSYS software based on establishing equation of vibration,so as to achieve natural frequency and fundamental vibration mode of structure,and also the displacement and stress of structure under nanomotion motor driving.Moreover,the analysis and comparison of rectangular-bridge and arch-bridge are made in order to prove the superiority of dynamic accuracy of the symmetrical-bridge structure. 相似文献
5.
As a new kind of supporting member, a prestress self balanced cable truss has been widely applied in point supported glass curtain walls. The free and forced vibration behaviors were analysed. Taking the temperature effect and geometric nonlinearity into consideration, the nonlinear vibration equation was derived with continua theory for prestress self balanced cable truss support system in point supported glass curtain wall. By the Galerkin method, the partial differential equation was transformed into ordinary differential equation and then solved with L P method and KBM method. With the case study, the effects of temperature, amplitude, and exterior excitation on the nonlinear vibration were discussed. And it was found that the frequency would decrease with increase of temperature and the nonlinear vibration showed the characteristics of hard spring. 相似文献
6.
The simplified mechanical model was proposed for frame supported multi ribbed composite wall beam. And the internal force of joist was calculated with the method of beam on the elastic foundation which takes the horizontal friction resistance into consideration. Moreover, a comparative analysis was employed with FEA program. It was found that it was necessary to consider the interfacial shearing force between wall and joist for the frame supported multi ribbed composite wall beam, otherwise, the performance of the composite would not exhibited sufficiently and the calculation error would be large. 相似文献
7.
The paper proposes the design method of robust H controller of vehicle seat suspension system. The dynamic model of seat suspension is developed,and the parameters uncertainties (mass, stiffness, damping) and stochastic vibration are introduced into the model system. Based on stochastic differential theory and Lyapunov functional, a semi controller is designed, and the controller parameters are solved by linear matrix inequality (LMI) which guarantees H performance index. The simulation results in time domain and frequency domain show that the controller designed for parameter uncertainties and stochastic vibration can attenuate the vertical acceleration of suspension system and improve riding comfort of human. 相似文献
8.
建立增速齿轮箱动力学分析有限元模型,利用Lanczos法求得齿轮系统的振动模态;以齿轮副时变啮合刚度激励、齿面综合误差激励和轮齿啮合冲击激励为内部作用激励,采用直接积分法求得箱体表面节点的动态响应。选取箱体上12个主要结构参数作为动力学性能优化的设计变量,齿轮箱体积为状态变量,以齿轮箱表面振动加速度的均方根值最小为动力学性能优化的目标函数,利用零阶与一阶优化算法求得最优设计变量。结果表明：优化前后箱体均不产生共振,且满足静力学条件;优化后目标函数减小37.5%,箱体各计算点的振动响应均有较大幅度的减小,最大减小量为54%。 相似文献
9.
The dynamic behavior of railway bridges (dynamic deflection and acceleration) is one of the running safety control indices for high speed trains. Therefore, the dynamic behavior of railway bridges is studied based on the concept of the dynamic signatures of the train and the bridge. By simplifying the train excitation as a series of moving concentrated forces, the mathematical expressions of the dynamic signatures of the train are obtained through theoretical derivations, and then a method is presented for calculating the resonance speed of trains and the maximum vertical acceleration of the bridge. With this method, the dynamic responses of the simple supported bridge can be calculated quickly. The feasibility of this method is validated through some examples, in which the resonance mechanism of train bridge system and the influencing factors are investigated. In addition, the effect of high frequency components to the bridge acceleration is also analyzed. 相似文献
10.
The vibration characteristic of engine mounting system is analyzed, the vibration model of engine mounting system is established, and calculation method of natural frequency and main vibration mode of mounting system is put forward. Then an engine mounting system with double - lined type isolator is presented. Isolation performance of engine mounting system is improved greatly by selecting elastic coefficient of isolator reasonably. 相似文献
11.
通过对全尺寸可拆式钢筋桁架模板在施工阶段的截面力学性能试验,研究了其在单调荷载作用下的破坏形态以及受力机理。并分别采用荷载挠度曲线法和极限弯矩法计算了截面特性。分析表明：施工阶段可以采用上下弦连续的桁架计算模型,荷载挠度曲线法计算结果与理论值偏差较大,其原因是：试件破坏过程由变形控制,而非强度,以及由于连接件与钢筋的相对滑移产生的附加挠度,极限弯矩法计算值与理论值较为吻合。在此基础上,给出了简支或等跨连续（两跨）梁计算模型的最大无支撑长度的建议值。 相似文献
12.
China Pavilion for Expo 2010 Shanghai is designed with peculiar style and special structural system. The main structure is composed of four concrete tubes with steel-concrete composite floors. It is designed with a shape of inverted trapezoid in elevation. The fundamental vibration mode of this structure is a torsional mode due to the special shape with greater moment of inertia in upper floor, which exceeds the limit value stipulated in Chinese code. The seismic analysis of prototype is carried out by ANSYS program to evaluate its overall seismic performance and improve the structural design. At the same time, shaking table tests of a 1/27-scale structural model are conducted. It is faund that although the first mode is torsional, the torsional responses are not so large, which agrees well with the results of shaking table tests. Both the test results and calculation results demonstrate that the designed structural system satisfies the seismic damage patterns and meets the pre-defined performance objectives. Based on the test results, suggestions for improving design are also put forward. 相似文献
13.
The analytic method for the free vibration of plane frame structure is presented. It is achieved by transforming the general eigenvalue problem of natural frequency and vibration mode of continuously distributed property system into typical boundary value problem of ordinary differential equation (ODE). A series of ODE, corresponding to the general eigenvalue problem, is formed, and then is solved by an general ordinary differential equation solver-COLSYS. Each component of a frame structure is regarded as an element in the analytic method. This makes it more efficient than that of finite element method which needs to increase elements to get the value of high-class natural frequency and vibration mode accurately. Some applications of the method show that it can solve the free bending vibration of plane-frame structure with various types of displacement constraint. The result indicates that this method is precise and efficient. 相似文献
14.
The two-way branch exhaust pipe shield is the main source of surface radiate noise of a vehicle's engine.(Using) the finite element analysis software ANSYS,a finite element model of the shield is established,and then the(modal) analysis is done theoretically with this model,the result is consistent with the experiment.The result shows that this finite element model can be used for the next structual dynamic characteristics analysis.With this model,the relationship of structural parameter,structural style of the shield and the corresponding vibrative modal is analyzed.The(optimal) improved measures are adopted which is based on the practical structure of the shield.The analysis of the(improved) structure shows that the increase of natural vibration frequency is visible,the vibration noise of the shield is suppressed distinctly. 相似文献
15.
With the development of high-speed and high-power, the motorcycle vibration from engine become one of the major factors affecting the performances of motorcycle. Elastic suspension structure is adopted between the engine and frame for the vibration during the process of designing a certain type of motorcycle with 200 cc engine in some enterprise.Through optimization of the suspension system performance parameters, inherent frequency of suspension system keeping away from the activated frequency of engine in common use is essential. Isolation performance is improved and the vibration is solved. As a result, the comfort is improved. 相似文献
16.
体育馆大跨度预应力次梁楼盖竖向振动模态分析 总被引：2，自引：0，他引：2
以重庆市铜梁县新城核心区小学建设项目3#楼（体育馆）工程为背景,对其大跨度预应力次梁楼盖竖向振动模态进行模拟分析,并与实测结果相比较,评价其控制竖向振动舒适度的效果。根据建模思路精确建立的该大跨楼盖有限元模型,其模态分析结果与模态实测结果接近,相对误差约为5%;模拟分析及工程实测结果表明,该大跨楼盖前三阶振型均以竖向振动为主,结构自振基频满足我国现行相关规范的要求,竖向振动舒适度符合标准;与无底板的大跨次梁楼盖相比,增加底板后,其增幅最小的一阶频率增长了19.9%,表明增加底板可有效地控制大跨度预应力次梁楼盖的竖向振动。 相似文献
17.
FU Guang-yao 《保鲜与加工》2005,(6):59-62
For light gauge steel floor,the structure testing and finite element method were applied to study the junior beam's inflection capability influenced by steel floor sheet.Analysis results show that the thin steel floor sheet affects junior beam's deflection very strongly.This conclusion has value for design of new structure or evaluating load support capability to the steel floors. 相似文献
18.
The paper aims to investigate natural frequency of delaminated advanced grid stiffened composite plates by hump resonance method.The composite laminated plate element and the rib element are adapted to simulate the laminated plate and the ribs.Based on the composite laminated plate and beam element model considering first-order shear effect,a damping model on the basis of Rayleigh damping model in conjunction with Adams' strain energy method(MSE) and a Hertz nonlinear dynamic contact model to avoid the overlap and penetration phenomenon between the upper and lower sub-laminates at the delaminated region.A numerical analysis method of dynamic response for the delaminated composite plates is carried out by precise time-integration method,and then the natural frequencies are achieved when the dynamic deflections reach the hump peak.For the frequency-domain analysis provided in the former research papers,it is a difficult problem to avoid the embedded phenomenon in the mode shapes at the delamination zone,while in the current time-domain analysis,the embedded phenomenon can be successfully overcome by using nonlinear contact model.By vibration excitation test,the specimens were excited by different excited frequency and the amplitude frequency response characteristics obtained are used to extract the frequency.The extracted frequencies of the narrow delaminated composite plates measured,which agrees well with the predicted natural frequencies. 相似文献
19.
The ride comfort of more than ten representative motorcycles is evaluated by the r. m. s acceleration value through road test. Then the investigation on ride comfort, with five grades, is carried out through these motorcycles rode by a dozen drivers. Using statistics and fuzzy mathematical methods, the fuzzy evaluation model of motorcycles ride comfort is built to discuss the relationship between the vibration magnitude and human reaction. Finally, according to this model, two motorcycles ride quality are evaluated. 相似文献
20.
According to test results of two different angle specimens of local transfer RC joint from inclined column to Beeline-shaped short shear wall under vertical static loads and results of corresponding finite element analysis(ANSYS), fundamental behaviors of the joint are achieved for the change of the angle.The result indicates that there is much difference in the stress distributions of the transfer beam and short shear wall for different angles of inclined column, which shows that the larger angle, the more great tensile force and the earlier crack in the transfer beam and the lower capacity. Otherwise, the angle is smaller, the evener stress distributions in short shear wall, the later crack, the worse degenerate in the transfer beam and the higher capacity.Furthermore, the mechanical behaviors of the joint obviously followed the characteristics of a truss model. 相似文献